1. Field Of The Invention
The present invention relates to improved thermally insulated window sash constructions and a uniquely configurated framing element for use therein.
2. Description Of The Prior Art
Numerous types of window constructions have been used previously in an effort to resist undesired heat loss from a building or undesired heat gain into a building. It has been known to place "storm windows" on the exterior of regular windows to minimize air leakage, conduction of heat and undesired condensation on the window interior during cold weather.
It has also been known to employ windows having two or more panes of glass with a dead air space therebetween. In connection with such windows which have been evacuated and sealed, problems have been encountered with air leakage and undesired condensation of moisture between the two panes of glass. Also, it has been known to employ metal frames such as aluminum frames for such windows. As aluminum is a good conductor of heat, condensation on the frames has resulted. Also, the aluminum surface could oxidize, scratch, pit or dent. It has also been known to provide thermal breaks in such frames to minimize thermal conduction through the sash frame.
It has also been known to employ vinyl sash frames in an effort to minimize heat conduction through insulated replacement window sash frames.
While a number of the above-described advances in the art have served to improve the efficiency through reductions in undesired heat transfer through conduction or leakage as well as condensation, there remains a very real and substanial need for further improvements in thermally insulated windows.